There is known a self-blocking differential of a transportation means, chosen by applicant as the prior art prototype, comprising a drive housing in which half-axial elements associated with half-axes are disposed coaxially to each other, and whose external surfaces are provided with helical grooves of opposite spiral directions; rolling members in the form of balls filling in a chain manner at least one closed-loop channel arranged in the housing. A portion of the closed-loop channel, forming an active branch, made open for insertion of segments of the balls into the helical grooves of the half-axial elements. The active branch is joined with a reverse longitudinal branch of the channel by means of lateral toroid-shaped sections of the channel. Besides, the reverse branch of the channel is also performed toroid-shaped with a width greater than one and less than two diameters of the balls (see the description of inventor certificate SU1507603 as of 7.11.87 published 15.09.89, B60K17/20, B.-O.A.Luci).
The mentioned prior art prototype should be considered to have a complicated design, related to the toroid-like shape of the channel. The balls are positioned in one row in the active branch of the channel. The reverse branch, having an essentially greater cross-section size (the width greater than one and less than two diameters of the balls) to place the balls therein in a checker order, combined with the toroid-like shape, complicates manufacturing the whole toroid-like channel, and substantially increases the differential's size.
Additionally, the shape of the closed-loop channel excludes an effective self-braking of the chain of the balls necessary for a full blockage of the automatic differential during a skidding of the transportation means. The self-braking means a force resisting to a displacement of the balls chain in the closed-loop channel. In the channel, having smooth toroid-like bends, the braking forces are very weak. Hence, to increase the forces of self-braking of the chain of the balls during their movement, the author of the prior art prototype needed to increase the diameter of the reverse channel. In such a channel, whose diameter is greater than one, but less than two ball diameters, the rolling members are placed in the checker order. During the movement of the chain of balls, they are burst (wedged) out aside, and a friction force developed between them and the channel's walls increases. Such design of a differential is characterized with low efficiency of the self-blocking device, and operation limitations thereof at low speeds, since self-blocking is basically carried out during acceleration of the transportation means.
In the prior art prototype (inventor certificate SU No 1507603, last paragraph of the description), it says: “ . . . forces, transmitted by the balls from one half-axial pinion (half-axial element) to the other, decrease on the portion of infinite channel, having any constructively chosen curvature and width of the channel depending on a necessary coefficient of blocking; while during the engine braking and backing up the self-blocking is less and practically depends on the efficiency of force transmission from one half-axial pinion to the balls, and on the efficiency of force transmission from the balls to the half-axial pinion.” Also, the re-position of the balls during the movement of the transportation means from a checker order to a single row requires a high precision of manufacturing of the whole closed-loop channel, increases the number of the balls and the dimensions of the entire device, and reduces its strength.
The technological aims of the claimed solution are: a simplification of design, reduction of the dimensions, and enhancing the technological performance, strength, and efficiency of self-blocking.